Subsurface apparatus for automatically filling conduit strings



Dec. 5, 1961 J. F. MUSE ErAL suBsuRFAcE APPARATUS FOR AUTOMATICALLYFILLING CONDUIT STRINGS 2 Sheets-Sheet 1 Filed Dec. 25, 1957 Dec. 5,1961 J. F. MUSE ErAL suBsuRFAcE APPARATUS FOR AUIOMATICALLY FILLINGcoNDUII STRINGS 2 lSheets-Sheet 2 Filed Dec. 23, 1957 INVENT ORS.

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United States Patent O ice 3,011,559 SUBSURFACE APPARATUS FOR AUTOMATI-CALLY FILLING CONDUIT STRINGS John F. Muse, Whittier, and William D.Myers, Norwalk, Calif., assignors to Baker Oil Tools, Inc., Los Angeles,Calif., a corporation of California Filed Dec. 23, 1957, Ser. No.704,603 16 Claims. (Cl. 166-225) The present invention relates tosubsurface well apparatus, and more particularly to apparatus forcontrollably tilling a conduit string, such as a string of casing ordrill pipe, with the fluid in the well bore as the conduit string islowered therewithin.

An object of the invention is to provide apparatus adapted to beincorporated in a conduit string for controllably allowing the conduitstring to ill automatically with the well bore fluid as it is lowered inthe well bore, in which circulation down through the conduit string canbe established at any time without altecting the ability of theapparatus to subsequently control lilling of the conduit string with thewell bore lluid.

Another object of the invention is to provide appara-tus adapted to beincorporated in a conduit string for automatically and controllablyfilling the conduit string with the fluid in a well bore, the apparatusembodying an upwardly closing back pressure valve held in an ineffectiveposition during such iilling 'of the conduit string and during the timethat circulation down through the conduit string is established, theback pressure Valve being placed in an effective condition wheneverdesired. At any time before rendering the back pressure valve effective,down-` lward pumping or circulation of fluid through the conduit stringcan take place without effecting the subsequent ability ofv theapparatus to controllably till the conduit string as it is lowered inthe well bore.

This invention possesses many other advantages, Iand -has other objectswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It

will now be described in detail, for the purpose of illustrating thegeneral principles of the invention; but it is to be understood thatsuch detailed description is not to be taken in a limiting sense, sincethe scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE. l is a longitudinal section -through -a well apparatus embodyingthe invention, with the lling valve closed;

FIG. 2 is a View similar toFlG. l, with the filling A f valve in openposition; Y

FIG. 3 is a view similar to lFIG. l, showing the condition of theapparatus during downward pumping or circulating .of fluid therethrough;

l FIG. 4 is a view similar to FIG. l, illustrating the back pressurev-alve released and `tluid being pumped downwardly through theapparatus.

The apparatus A disclosed in the drawings is ldesigned to form part of astring of well casing B, C to be run in -a well bore D. As specificallyshown, the apparatus may yform part of a casing collar constituting partof the' casing string. It is to be understood, however, that theapparatus can also be incorporated in a casing string at its lower end,whereupon it would be considered to be a casing shoe. Moreover, theapparatus can be placed at any desired point in a string of drill pipe,or Vother co-nduit string, to be disposed in a well bore.

The apparatus A includes an outer tubular member 1V having an upperthreaded box 11 for threaded attachment v Patented Dec. 5, 1961 tothelower end of an adjacent upper casing section B, such casing sectionforming part of the casing string extending to the top of the Well bore.The tubular member also includes a lower pin 12 threadedly attached tothe upper boX 13 of an adjacent lo-wer casing section C. The tubularmember has a cementitious plug 14 cast therein, circular ribs 15 on theplug being formed in the casting operation by internal grooves 16 in thetubular member to inseparably unite the parts against relative movement.

The cementitious plug 14 has a central passage 17 therethroughsurrounded by a valve seat 18 cast within the plug. This valve seat isengageable yby a back pressure valve element 19, disclosed as being inthe form of a flapper valve mounted on a pivot pin 20y suitably securedto the valve seat. This valve element is normally urged in an upwarddirection into engagement with its cornpanion seat 18 by a spring 21wound around the hinge pin 20, one arm 22 of the spring bearing againstthe valve seat, and the other arm 23 bearing against the ilapper valvehead 19 itself. Y

The valve seat 18 actually forms part of an upper housing section 24depending from the seat and piloted within the upper end of a lowerhousing section 25. Both of o these housing sections are inseparablykunited to the cementitious plug. The upper housing section 24 may have acut-outportion or window 26 to allow the apper head valve -19 to swingdownwardly away from engagement with its seat and substantiallycompletely out ofthe path of the iluid flowing to and from the seat, asdescribed hereinbelow. y

For the purpose of maintaining the Valve member 19 out of engagementwith the seat during lowering of the casing string through the fluidinthe well bore, so as to allow the well bore lfluid to flow upwardlythrough the apparatus and into the casing B thereabove, tocontrollab'ly` till the casing string with the well bore fluid up to apredetermined level, which may preferably be less than the level of theiluid externally of the casing string, and to permit downward pumping ofiiuid through the apparatus A at -any time `during the operation oflowering the casing in the well bore, without interfering withsubsequent controllable iilling of the casing stringwith the well borefluid, a valve device 27 is embodied in the tubular member 10 primarilylbelow the back pressure valve 19, this device being disposed within thehousing sections 24, 25.

Y The valve device for controllably filling the well bore with tluidincludes a tubular valve member 28 slidable lalong the wall of the lowerhousing section 25. .This

. tubular valve member has an upwardly projecting tubular portion, skirtor sleeve 29 releasably secured t-o it by one or more shear screws orpins 30, which tubular portion is adapted to engage the apper valve head19 and maintain it in open position within the upper housing window 26and substantially completely to one side of the path of iluid owingthrough the apparatus. It is preferable Ithat the tubular portion orextension sleeve 29 extends completely across the flapper valve member19' when the latter is in open position, and, in fact, it may extendinto they valve seat 18- itself for the purpose of insuring theretention of the back pressure apper valve head 19 in an ineffectiveposition, and to prevent contact of the fluid in the casin-g stringtherewith while in such ineffective position. The sleeve valve member 28is movable upwardly wit-hin the lower housing section 25, such upwardmovement being determined by engagement of the shoulder 31`thereon withan inwardly projecting shoulder 32 formed at the lower end of the upperhousing sectionY 24. Downward movement of the valve member in the lowerhousing section is limited by engagement of a,

lower intermediate shoulder 33 thereon with a companion internalshoulder 34 in the lower housing section. When in this position (FlG.l), the valve extension 29 is still in engagement with the flapper valvehead 19, preventing the spring 21 from shifting the latter to its closedposition in engagement with its companion seat 18.

The lower inner edge 35 of the valve member 28 is engageable with theenlarged head portion 36 of a valve seat structure 37, having adepending stem portion 38 extending slidably through the central hub 39of a spider d@ which is connected to, or integral with, the lowerhousing section 25 by a plurality of radially arranged circumerentiallyspaced ribs 41. Upward movement of the seat 37 within the housing islimited by engagement of a stop nut 42 threaded on the lower end of thestem 3 8 with the lower end of the spider hub 39. The seat 37 1s urgedin an upward direction by a helical compression spring 43 surroundingthe stern 3S, its lower end engaging the upper end of the hub 39 and itsupper end the head portion 36 of the seat 37. The seat 37 can movedownwardly away from the tubular valve member 23 against the force ofthe helical spring 43.

The fluid in the well bore can low upwardly into the lower end of thehousing through the spider openings 44 between the ribs 41 and throughthe valve housing. This uid may shift the sleeve valve 28 in an upwarddirection away from engagement with the seat 37, whereupon it cancontinue llowing upwardly through the large diameter passage 45 throughthe sleeve valve, through the extension sleeve 29, past the apper valvehead 19, and through the valve seat 1S for continued upward flowing intothe casing section B above the collar A. The ability of the fluid to owupwardly in this manner, is dependent upon the relative hydrostaticheads of fluid internally and externally of the casing string, whichdetermines the engagement or non-engagement of the slidable sleeve valvemember 28 with its companion seat 37. It is preferred that the fluidlevel in the casing string remain at a substantially lower point thanthe external fluid level, to insure that the lluid entering the wellcasing will not overow at its upper end and wet the surface equipmentand personnel.

One manner of accomplishing the aforementioned objectives is toconstitute the tubular valve member 2S as a valve device havingdifferential upper and lower areas. Thus, the lower housing section 25has an upper large diameter cylindrical wall 50, and an adjacent lowercylindrical wall 51 of smaller internal diameter, which are separatedbythe aforementioned stop shoulder 34. The slidable valve member 28 has acorresponding large diameter upper portion 52 adapted to slide along theupper wall 50, and a smaller diameter portion 53 slidable along thelower cylindrical wall 51. When the valve member 28 moves in a downwarddirection to place its sealing edge 35 in engagement with the valve seatsurface 54 on the head for the purpose of preventing upward passage offluid through the apparatus, the transverse shoulder 33 on the largediameter portion of the tubular valve member may engage the housingshoulder 34. At the same time, the tubular valve extension 29 is stillin contact with and disposed across the flapper valve head 19 to hold itto one side of the upper housing section in a wide open position, out ofengagement from its seat 18, to protect the valve head 19 from theerosive action of the fluid owing longitudinally through the apparatus.

Suitable slidable types of seals 55 are provided between the cylindricalwalls 50, 51 of the housing section and the valve member 28. Rubber orrubber-like seal rings 55 are disposed on the large and smaller diameterlportions 52, 53 of the valve member for slidable sealing with thecompanion large and smaller diameter cylindrical walls 50, 51 of thehousing section 25. These seals cooperate with the valve member 28 andthe housing section 25 to form a confined annular cylinder space intowhich the well fluid cannot enter, this space containing air atsubstantially atmospheric pressure.

Since the smaller cylinder 51 has a lesser diameter than the largercylinder 50, and the lower portion 53 of the valve member has acorresponding lesser diameter than the diameter of the upper portion 52of the valve member, the downwardly facing area R of the valve member 28over which fluid can act to urge the valve 28 in an upward direction, issubstantially less than the upwardly facing area S over which the lluidabove the valve member 28 can act. Thus, the annular area R between thesealing edge 35 of the valve member and the smaller diameter cylinderwall 51 is less than the annular area S between an upwardly cylindricalprolongation of this sealing edge 35 and the larger diameter cylinderwall 50. Accordingly, fluid under pressure below the valve mem- -ber 28,which corresponds to the hydrostatic head of lluid externally of thecasing string B, C,y is acting over the area R, to urge the valve member28 in an upward direction out of engagement from its companion seat 37.The pressure of the iluid within the casing string B, C, whichcorresponds to the hydrostatic head of fluid therewithin, is acting in adownward direction over the area S of the valve member 2S, tending tourge the latter in a downward direction into engagement with the valveseat 37. A balanced condition on the valve 2.8 4will be realized whenthe pressure acting upwardly onV the valve member over the area Rvexerts a total force which is equal to the pressure acting on the valvemember in the opposite direction over the area S. Since the `area R isless than the area S, a balanced condition will be obtained when thereis a lesser pressure internally of the casing string than existsexternally thereof. Expressed by way of formula, a balanced conditionwill exist when:

P1R=P2S in which: P1=`the hydrostatic head of fluid externally of thecasing string; and P2=the hydrostatic head of fluid internally of thewell casing.

The hydrostatic heads of fluid externally and internally of the wellcasing will, therefore, be inversely proportional to the areas S and R.Since the area S is greater than the area R, the hydrostatic head offluid internally of the well casing will be less than the hydrostatichead of uid externally of the well casing, for a balanced condition toexist. As the hydrostatic head of uid within the well casing increasestoa further extent, it will shift the valve member 2S downwardly intoengagement with the valve seat 37, preventing further upward passage offluid into the well casing B, C, until the casing string has beenlowered in the well bore uid to a further extent.

The apparatus is run in the well bore with the parts loccupying eitherof the relative positions shown in FIGS.

1 and 2. During such lowering, the hydrostatic head of fluid around thewell casing B, C will act over the area R of the valve member 28 toshift it out of engagement from the valve seat (FIG. 2), or to openposition, allowing the uid to ow upwardly around the valve seat 37 andthrough the tubular valve member 28, moving upwardly through thetubularextension sleeve 29 past the liapper valve head 19 and on into thecasing string section B above the collar apparatus A. If the casingstring is brought to rest, as for the purpose of adding another casingsection at the top of the hole, the lluid will ow therewithin until itrises to a level satisfying the aforenoted equation, and when the leveltends to exceed the amount indicated by the equation, then the pressureof the fluid within the well casing will shift the valve member 28downwardly into engagement with the valve seat 37, as disclosed in FIG.1, preventing further passage of fluid upwardly into the well casing.Such pressure of the fluid within the well casing cannot shift the valveseat 37 in a downward direction since the external hydrostatic head ofiluid acting upwardly on thevalve seat 37 exceeds the internal pressureacting downwardly on this seat, the external pressure being assisted Vinholding the valve seat in an upward position by the helicalv compressionspring 43.

If the descent of the casing string in the well bore fluid isrecommended, the valve 28 will then slide upwardly to open position, asindicated in FIG, 2, and additional luid will enter the casing string.The above actions will continue alternately with the valve 28 shiftingbetween open and closed positions until the casing B, C has been loweredto the desired depth in the well bore. The level of the tiuid in thewell casing, however, will always be maintained at a lower point thanthe level of the fluid in the well bore D externally of the well casing,depending upon the relationship of the aforenoted areas R and S. Duringall of this time, the tubular extension 29 projecting above the sleevevalve 28 is engaging the flapper valve head 19 to keep it in fully openposltion, and completely to one side of the iiuid flowing upwardlythrough the sleeve valve 28, so as not to interfere therewith, nor to befluid cut thereby.

If at any time during the lowering of the casing string n the well bore,it becomes necessary or desirable to circulate or pump iluid downthrough the casing string B, C, such action can occur without aifectingthe subsequent ability of the apparatus to controllably lill the casingstring. Fluid is pumped into the casing string, the increasing of thefluid level relative tothe. external hydrostatic head shifting thetubular valve member 28 downwardly until it engages the housingVshoulder 34. The fluid pumped down the casing string will now passthrough the extension sleeve 29 and the tubular valve member 23, forcingthe valve seat 37'downwardly against the action of its Yspring 43 andpassing through the spider 40 into the casing section or sections Btherebelow, for discharge from the casing string into the well bore D.Such condition of the apparatus is illustrated in FIG. 3, in whichrit isevident that the extension sleeve 29 is rstill disposed fully across theflapper valve head 19 to vpre-A vent its shifting to closed position,and from being subject to the erosive action of the fluid being pumpedthrough the apparatus.

After the circulation of fluid downwardly through the casing string hasceased, the spring 43 will shift the valve seat 37 upwardly intoengagement with the tubular valve member 2S, closing the'central passagethrough the latter. The casing string B, C can then be lowered to afurther extent in the well bore, the tubular valve member 28 remainingin .a downward position closed against its companion seat 37, until thecasing string has been' lowered sufliciently to bring its internal uidlevel sufficiently below the tluid level or hydrostatic head externallyof the casing string, in which the external pressure acting over the endarea R of the Valve member 28 can overcome the internal pressure actingover the en d area S of the tubular valve member. When this occurs, andas the casing string is lowered to a further extent through the fluid inthe well bore, the tubular valve member 28 moves upwardly away from itsvalve seat 37,' which can only be shifted upwardly by its spring 43 tothe extent determined by engagement of vthe stop nut 42 with the spiderhub 29, allowing the well bore fluid to ow through the apparatus A andinto the casingstring B, Conce` again. Y When-the fluid level reachesthe predetermined value governed by the aforenoted equation, theYtubular valve member 28 will again be shifted downwardly intoengagement with the valve seat 37, to prevent further upward flow of uidthrough the casing string, until the latter has been lowered to a stillfurther level in the well bore.

At any time, circulation of fluid can be establishedk v downwardlythrough the casing string B, C without affect'-v ing the ability of theapparatusrto operate subsequently to automatically and controllably lillthe casing string 6 with the well bore fluid as the casing string isbeing lowered in the well b'or'e.

At any time that the back pressure valve device -19 is to be renderedoperative, as after the casing has been lowered to the required extentin the well bore, andprior to the cementing of the well casing B, C inthe well bore, a tripping ball 60,which may be rather heavy, is droppedinto the casing string at the top of the hole and is leither pumped orallo-wed to gravitate through the casing string until it enters theextension sleeve 29 and comes to rest upon a lower valve seat 61 in theextension sleeve immediately above a plurality vof side ports 62therein. Such engagement of the trip ball 60 with the extension sleeveseat 61 closes the passage through the latter, allowing the pressure ofthe fluid in the casing string above the ball and sleeve to beincreased, Since the tubular valve member 28 is engaging the housingshoulder 34 and cannot move downwardly, the pressure acting downwardlyon the ball 60 and the extension sleeve 29 is tending to disrupt theshear screw or screws 30. When the pressure exceeds the shear strengthof the screw or screws 30, the latter are disrupted and the extensionsleeve 29 then shifted downwardly in the tubular valve member 28 intoengagement with the valve seat 37, the upper end of the extension sleevemoving past the lower endof the flapper valve head 19, which is thenfreed to be urged in an upward direction` by its spring 21 intoengagement with the valve Aseat 18. If Huid is now pumped down throughthe casing string B, C it will automatically swing the vflapper valvehead 19 downwardly away from its seat 18, and will also forcetheextension sleeve 29 downwardly against the valve seat 37,fshiftingthe latter in a downward direction against the force of the compres--sion spring 43 to dispose the side ports 62 in the extension sleevebelow the lowerkend of the tubular valvemember 28. The uid can then pass,down through the 'A upper central passage 17 in the apparatus past theilapper valve head 19, through the tubular extension sleeve 29, throughthe side ports 62 in the latter to a position below the l'tubular' valvemember 28, and through the spider` openings 44 into the casing Ctherebelow (FIG, 4).

.After the hole D has been properly conditioned by crrculatmg fluid downthrough the casing, which will then ilow upwardly through the annulusaroundvthe Vcas,

ing, cementitious material, such as cement slurry, can be pumped downthe casing string B, flowingthrough the apparatus` A, which will then bein a condition illustrated in FIG. 4, into the lower casing section B,and thence outwardly into the annulus around the casing B, C 110W-,

ing upwardly through the annulus. When the pumping ceases, the cementslurry and the like cannot flow back into the casing string and throughthe apparatus A, since the apper valve head 19 will move upwardly intoengagement with its seat 18, to preclude such upward flow,

It is, accordingly, apparent that an apparatus has been provided forcontrollably lling a casing string, or the like, during its loweringthrough the fluid in the well casing. Downward circulationthrough thecasing' string a back pressure valve can 'be rendered effective toprecan be accomplished at any time, followed by subsequent controlledfilling of the casing string as it is being low` ered in the well boreto a further extent. AtV any time,

vent upward `or return iiowv of fluid into and through the casingstring. i l

The inventors claim:

l. In well apparatus: a tubular member adapted to' form partV of aconduit string to be lowered in awel] bore; a valve device in saidtubular member for allowing upward and downward flow 'of fluid in saidtubular member, said device including first and second valve membersengageable with each other to prevent upward .l flow of tluid throughsaid tubular member, means mount-` mg said rst valve member for,movement 4away from said second valve member to permit upward flow ofiluid throughY said tubular member, means mounting said sec# ond valvemember for movement away from saidl first'y valve member to permitdownward ow of uid through said tubular member, said rst valve memberhaving a resultant transverse area subject to the pressure of the fluidin the conduit string above the rst valve member substantially greaterthan the resultant transverse area of said irst valve member subject tothe pressure of the uid in the conduit string below the lirst valvemember, and means for shifting said second valve member back intoengagement with said first valve member after said second valve memberhas been moved away from said iirst valve member and whilesaid rst valvemember is adapted to move away from said second valve member to permitupward flow of uid through said tubular member.

2. In well apparatus: a tubular member adapted to form part of a conduitstring to be lowered in a well bore; a valve device in said tubularmember for allowing upward and downward flow of iluid in said tubularmember, said device including upper and lower valve members engageablewith each other to prevent upward flow of fluid through said tubularmember, means mounting said upper valve member for upward movement awayfrom said lower valve member to permit upward ow of iiuid through saidtubular member, means mounting said lower member for downward movementaway from said upper valve member to permit downward flow of liuidthrough said tubular member, said upper valve member having a resultanttransverse area subject to the pressure of the fluid in the conduitstring above said upper Valve member substantially greater than theresultant transverse area of said upper valve member subject to thepressure of the uid in the conduit string below the upper valve member,and means for shifting said lower valve member upwardly back intoengagement with said upper valve member after said lower valve memberhas moved downwardly away from said upper valve member and while saidupper valve member -is adapted to move upwardly away from said lowervalve member to permit upward tlow of uid through said tubular member.

3. In well apparatus: a tubular member adapted to form part of a conduitstring to be lowered in a well bore; a Valve device in said tubularmember for allowing upward and downward flow of uid in said tubularmember, said device including first and second valve members engageablewith each other to prevent upward flow of fluid through said tubularmember, means mounting said iirst valve member for movement away fromsaid second valve member to permit upward flow of fluid through saidtubular member, means mounting said second valve member for movementaway from said rst valve member to permit downward ow of fluid throughsaid tubular member, said rst valve member having a resultant transversearea subject to the pressure of the fluid in the conduit string abovethe first valve member substantially greater than the resultanttransverse area of said rst valve member subject to the pressure of thefluid in the conduit string below the first valve member, and springmeans engaging said second valve member to shift said second valvemember back into engagement with said rst valve member after said secondvalve member has been moved away from said rst valve member and whilesaid first valve member is adapted to move away from said second valvemember to permit upward flow of uid through said tubular member.

4. In well apparatus: a tubular member adapted to form part of a conduitstring to be lowered in a well bore; a valve device in said tubularmember for allowing upward and downward flow of uid in said tubularmember, said device including upper and lower valve members engageablewith each other to prevent upward flow of` fluid through said Vtubularmember, means mounting said upper valve member for upward movement awayfrom said lower valve member to permit upward flow of tiuid through saidtubular member, means mounting said lower member for downward movementaway from said upper valve member to permit downward ow of iluid throughsaid tubular member, said upper valve member having a resultanttransverse area subject to the pressure of the fluid in the conduitstring above said upper valve member substantially greater than theresultant transverse area of said upper valve member subject to thepressure of the Huid in the conduit string below the upper valve member,and spring means engaging said lower valve member for shifting saidlower valve member upwardly back into engagement with said upper valvemember after said lower valve member has moved downwardly away from saidupper valve member and while said upper valve member is adapted to moveupwardly away-from said lower valve member to permit upward flow offluid through said tubular member.

5. In well apparatus: a tubular member adapted to form part of a conduitstring to be lowered in a well bore; a valve seat in said tubularmember; a tubular valve member slidable downwardly in said tubularmember into engagement with said seat and upwardly from engagement withsaid seat; means mounting said valve seat in said tubular member foraxial sliding movement upwardly into engagement with said valve memberand downwardly from engagement with said valve member; said tubularvalve member having a resultant transverse area subject to the pressureof the iiuid in the conduit string above the tubular valve membersubstantially greater than the resultant transverse area of said tubularvalve member subject to the pressure of the fluid in the conduit Stringbelow the tubular valve member, and spring means engaging said valveseat to urge said valve seat upwardly into engagement with said valvemember.

6. In well apparatus: a tubular member adapted to form part of a conduitstring to be lowered in a Well bore; a valve seat in said tubularmember; a tubular valve member slidable downwardly in said tubularmember into engagement with said seat and upwardly from engagement withsaid seat; means mounting said valve seat in said tubular member -foraxial slidable movement upwardly into engagement with said valve memberand downwardly from engagement with saidvalve member; said tubular valvemember having a resultant transverse area subject to the pressure of theHuid in the conduit string above the tubular valve member substantiallygreater than the resultant transverse area of said tubular valve membersubject to the pressure of the fluid in the conduit string below thetubular valve member, spring means engaging said valve seat to urge saidvalve seat upwardly into engagement with said valve member; and stopmeans engageable with said tubular valve member to limit its downwardmovement in said tubular member; said valve seat being movabledownwardly away from said valve member against the force of said springmeans when said valve member engages said stop means.

7. In well apparatus: a tubular member adapted to form part of a conduitstring to be lowered in a well bore; a valve seat in said tubularmember; a tubular valve member slidable downwardly in said tubularmember into engagement with said seat and upwardly from engagement withsaid seat; means mounting said valve seat in said tubular member foraxial slidable movement upwardly into engagement with said valve memberand downwardly from engagement with said valve member; said tubularvalve member having a resnltanttransverse area subject to the pressureof the fluid in the conduit string above the tubular valve membersubstantially greater than the resultant transverse area of said tubularvalve member subject to the pressure of the uid in the conduit stringbelow the tubular valve member, spring means engaging said Valve seat tourge said valve seat upwardly into engagement with said valve member;and

9 stop means engageable with said seat to limit its upward movement insaid tubular member while permitting its downward movement away fromsaid tubular valve member.

8. In well apparatus: a tubular member adapted to form part of a conduitstring to be lowered in a well bore, said tubular member having apassage therethrough through which uid can ow in both upward anddownward directions; back pressure valve means in said tubular memberadapted to prevent upward flow of iluid through said tubular memberwhile permitting downward flow of fluid therethrough; a valve device insaid tubular member below said back pressure'valve means for allowingupward and downward iiow of uid in said tubular member upon opening ofsaid device and to prevent such upward and downward flow of fluid uponclosing of said device; means engaging said back -pressure valve meansto hold it in open condition to permit upward flow of uid through saidtubular member; and means releasably securing said holding means to saidvalve device While said valve device is conditioned ytoy allow bothupward and downward iiow of fluid in said tubular member, said securingmeans being releasable to permit downward shifting of said holding meansto a position permitting closing of said back pressure valve means.

9. In well apparatus: a tubular member adapted to form part of a conduitstringV to be lowered in a well bore; back pressure valve means in saidtubular member adapted to prevent upward flow of fluid through saidtubular member; a valve device in said tubular member for allowingupward and downwardl flow of fluid in said tubular member upon openingof said device and to prevent such upward and downward iiow of fluidupon closing of said device; means engagingfsaid back pressure valvemeans to hold it in open condition to permit upward flow of uid throughsaid tubular member; means releasably securing said holding means inposition engaged with said back pressure valve means while said valvedevice is conditioned to allow both upward and downward flow of ilud insaid tubular member; and means adapted to be sent down the conduitstring from the top of the well bore for eiecting release of saidsecuring means and shifting of said holding means to a position allowingsaid back pressure valve means to close.

l0. In well apparatus: a tubular member adapted to form part of aconduit string to be lowered in a well bore; back pressure valve meansin said tubular member adapted to prevent upward iiow of fluid throughsaid tubular member; a valve device in said tubular member below saidback pressure valve means for allowing upward and downward flow of fluidin said tubular member upon opening of said device and to prevent suchupward and downward iiow of uid upon closing of said device; tubularmeans engaging said back` pressure valve means to hold it in opencondition to permit upward iiow of uid through said tubular member, saidtubular means having a valve seat; means releasably securing saidtubular means in position engaged with said back pressure valve meanswhile said valve device is conditioned to allow both upward and downwardflow of uid in said tubular member; and means adapted to be sent downthe conduit string from the top of the well bore into engagement withsaid valve seat to enable said securing means to be released and saidtubular means shifted downwardly to a position allowing said backpressure valve means to close.

1l. In well apparatus: a tubular member adapted to form part of aconduit string to be lowered in a well bore; back pressure valve meansin said tubular member adapted to prevent upward flow of fluid throughsaid tubular member; a valve device in said tubular member upon openingof said device and to prevent such upward and downward iiow of lluidupon closing of said device for allowing upward and downward ilow ofiluid in said tubular member; tubular means engaging said back pres'-sre valve 'means to hold it in open condition to permit upward ilow ofiluid through said tubular member, said tubular means having a valveseat; means releasably securing said tubular means to said valvedevicein a position engaged with said back pressure valve means whilesaid valve device is conditioned to allow both upward and downward ilowof liuid in said tubular member; vand means adapted to be sent down theconduit string from the top of the well bore into engagement with saidvalve seat to enable said securing means to be released, and saidtubular means shifted downwardly to a position allowing said backpressure valve means to close.

12. In well apparatus: a tubular member adapted to form part of aconduit'string to be lowered in a well bore; a first valve seat in saidtubular member; a valve element movable upwardly into engagement withsaid seat to prevent upward ow of iluid through said tubular member; asecond valve seat in said tubular member; a tubular valve member movabledownwardly in said tubular member into engagement with said second seat;spring means engaging said second seat to urge said second seat upwardlyinto engagement with said valve member; a tubular extension; meansreleasably securing said extension to said tubular valve member and inposition engaged with said valve element to prevent said element fromengaging said first seat; and means adapted to be sent down the conduitstring into enga-gement with said extension to release said securingmeans and shift said extension from said element to permit said elementto engage said rst seat.

13. In well apparatus: a tubular member adapted to form part of aconduit string to be lowered in a well bore; a rst valve seat in saidtubular member; a valve element movable upwardly into engagement with`said seat to prevent upward flow of fluid through said tubular member; asecond Valve seat in said tubular member; a tubular valve member movabledownwardly in said tubular member into engagement'with said second seat;spring means engaging said second seat to urge said second seat upwardlyinto engagement with said valve member; a tubular extension; meansreleasably securing said eXtension to said tubular valve member and inposition engaged with said valve element to prevent said element fromengaging said rst seat; and means for releasing said securing means topermit shifting of said extension from said element and engagement ofsaid element with said first seat.

I 14. In well apparatus: a tubular member adapted to form part of aconduit string to be lowered in a well bore; a first valve seat in saidtubular member; a valve element movable upwardly into engagement withsaid seat to prevent upward flow of iluid through said tubular member; asecond valve seat `in said tubular member; a tubular valve membermovable downwardly in said tubular member into engagement with saidsecond seat; spring means engaging said second seat to urge said secondseat upwardly into engagement with said valve member; a tubularextension; means releasably securing said extension to said tubularvalve member and in position engaged with said valve element to preventsaid element from engaging said first seat; means adapted to be sentdown a conduit string into engagement with said extension to releasesaid securing means and shift said extension from said element to permitsaid element to engage said irst seat; and stop means engageable withsaid tubular valve member to limit its downward movement in said tubularmember; said second valve seat being movable downwardly away from saidtubular valve member when said tubular valve member engages said stopmeans.

15. In well apparatus: a tubular member adapted to form part of aconduit string to be lowered in a well bore; a iirst valve seat in saidtubular member; a valve element movable upwardly into engagement withsaid seat to prevent upward iiow of fluid through said tubular member; asecond valve seat in said tubular member; a tubular valve member movabledownwardly in said tubular member into engagement with said second seat;spring means engaging said second seat to urge said second seat upwardlyinto engagement withsaid valve member; a tubular extension; meansreleasably securing said extension to said tubular valve member and inposition lengaged with said valve element to prevent said element fromengaging said first seat; means adapted to be sent down a conduit stringinto engagement with said extension to release said securing means andshift said extension from said element to permit said element to engagesaid rst seat; stop means engageable with said tubular valve member tolimit its downward movement in said tubular member; said second Valveseat being movable downwardly away from said tubular valve member whensaid tubular valve member engages said stop means; and stop meansengageable with said second seat to limit its upward movement in saidtubular member.

16. In well apparatus: a tubular member adapted to form part of aconduit string to be lowered in a well bore; a first valve seat in saidtubular member; a valve element movable upwardly into engagement withsaid seat to prevent upward flow of Huid through said tubular member; asecond valve seat in said tubular member; a

tubular valve member movable downwardly in said tubu# lar member intoengagement with said second seat; spring means engaging said second seatto urge said second seat upwardly into engagement with said valvemember; a tubular extension; means releasably securing said extension tosaid tubular valve member and in position engaged with said valveelement to prevent said element from engaging said iirst seat; and meansadapted to be sent down a conduit string into engagement with saidextension to release said securing means and shift said extension fromsaid element to permit said element to engage said rst seat; saidextension being shiftable against said second seat to shift said secondseat from said tubu-` lar valve member, said extension having an openingthrough which uid can flow when said extension is disposed against saidsecond seat.

References Cited in the file of this patent UNITED STATES PATENTS gpo vpar

